1. Field of the Invention
This invention relates to the reclamation or reconditioning of used lubricating oils, e.g., used turbine and/or circulating oils. More specifically, it relates to a process or method wherein soluble metal salts present in such used oils are removed economically and efficiently as sediments thereby retarding the deterioration and sludge formation of the oils.
2. Description of Prior Art
The oxidation of turbine/circulating oils in the presence of metals can often result in the formation of soluble metal salts. Used turbine/circulating oils therefore usually contain soluble metal salts which act as oxidation catalysts to accelerate oil deterioration. Thus, removal of these catalytically active metal salts retards the deterioration and sludge formation of the oils, thereby providing longer service life. However, it is difficult to remove such salts even with ultrafine filtration or ultracentrifugation. Oil users, accordingly, make little or no attempt to remove them because as stated supra no simple method is available. The novel method that we have developed has demonstrated that removal can be achieved easily and economically. Also, conceptually, this novel method can be utilized in the rerefining of waste lubricating oils and also in removing undesirable metal salts in commercial processes of catalytically cracking hydrocarbon feeds. Nevertheless, the present invention is particularly directed to the reclamation of used turbine and/or circulating oils by eliminating soluble metal salts produced from oil deterioration (oxidation).